Shock absorber for use in a vehicle

ABSTRACT

A shock absorber according to the present invention for use in a vehicle for cushioning a vibration generating between a vehicle body and an axle, in which a suspension spring is disposed between one member which may serve as a mass below the spring and the other member which may serve as a mass above the spring, has an apparatus for adjusting the height of vehicle permits its mounting length to be adjusted without changing an initially set load of the suspension spring while being relatively displaced with respect to the one member so that a stroke of the shock absorber may be changed.

This is a divisional of copending application Ser. No. 07/376,879 filedon Jul. 7, 1989, U.S. Pat. No. 5,009,451.

FIELD OF THE INVENTION

The present invention relates to a shock absorber for use in a vehiclefor cushioning a vibration caused between a vehicle body and an axle, inwhich a suspension spring is disposed between one member which may serveas a mass positioned above the spring of the shock abosorber and theother member which may also serve as a mass positioned below the same.

BACKGROUND OF THE INVENTION

In the latest automatic two-wheeled vehicle, an apparatus for adjustinga height of the vehicle has often been provided so that rider's feetcannot only reach the ground to stop the vehicle when running on theurban area but also a performance of the vehicle as covering a wastelandmay be improved. There have conventionally been two kinds of a rearcushion type apparatus: one is a type in which an initially set load canbe changed and the other to a type in which its entire length can bechanged.

A rear cushion having an apparatus for adjusting the height of vehicle,in which the initially set load can be changed, is known from, forexample, U.S. Pat. No. 4,159,105. Its schematic views are shown in FIGS.10 to 12, in which reference numeral 1 is a damper cylinder, 2 a piston,3 a piston rod, 4 a suspension spring, 5 a rebound spring, 6 a stopperrubber, 7 a member for mounting the piston rod 3, around which acylinder 11 for adjusting the height of vehicle is formed as one memberfor adjusting the height of vehicle. 8 is a mounting member used foreither one of the vehicle body and axle, 9 the other remaining mountingmember used for the vehicle body or axle, 10 a piston for adjusting theheight of vehicle, which is arranged as the other member for adjustingthe same, the piston vertically sliding within the above-mentionedadjusting cylinder, with one end of the suspension spring supportedthereagainst. FIG. 10 relates to a state in which the suspension spring4 is set to be slightly compressed in an initially loaded state, i.e.,when the piston rod 3 is withdrawn to maximum extent out of the cylinderuntil the rebound spring 5 is completely compressed, the state being onein which the shock absorber is extended to maximum extent. FIG. 11illustrates a state in which since a rider rides on the vehicle thesuspension spring 4 is compressed from a position of FIG. 10 and amounting length is shortened and yet the height of vehicle is notadjusted yet, the state being suitable for running on the urban areabecause his feet can reach the ground. FIG. 12 illustrates a state inwhich when the rider rides on the vehicle and runs into a wasteland ahydraulic oil is supplied into the cylinder for adjusting the height ofvehicle formed about the member 7 for mounting the piston rod tooutwardly displace the member 7 with the result that the height ofvehicle is increased from L₁ to L₂. l_(t) is a total stroke, l₁ acompession stroke, and l₂ a rebound stroke. (Actually, although thestroke 1_(t) equals a value obtained by deducting a compressed length ofthe rebound spring and the basic lengthes assumed by, for example, anoil seal and rod guide and the like at the end of a bore of thecylinder, in this case, it is represented as such including them forconvenience of description. Unless otherwise specified, the same appliesto the following part of this specification.)

If a displacement vs. load curve of the suspension spring is graphicallyplotted in which an initial load is set, then K₁ is obtained as in FIG.13. I₁ is the value of the initial load. If the initiallly set load isvaried from I₁ to I₂, then the displacement vs. load curve is plotted asK₂. If the piston 10 for adjusting the height of vehicle is now upwardlydisplaced from a position of the lower end within the cylinder of FIG.11 to increase the initially set load of the suspension spring, then,since the load applied to the suspension spring is the same as beforeadjusting the height of vehicle, the piston rod is withdrawn by thatdisplacement of the piston 10 from a damper cylinder 1 to increase theheight. Consequently, the rider will feel rather stiff to ride on thevehicle because the initiallly set load of the suspension spring isincreased. Besides, since the total stroke l_(t) of the hydraulic shockabsorber remains the same before (FIG. 11) and after (FIG. 12) theheight is increased, even if he increases the height of vehicle after heruns into the wasteland, a great shock cannot be absorbed. Further,although the total stroke l_(t) remains the same before and after theheight is increased, the position of the piston in 1G state is changedand the distributions of stroke at the compression and extension sidesbecome different with each other. As a result, they respectively assumea relationship of the strokes: compression side stroke l₁ ' and therebound stroke l₂ ', and when the height of vehicle is increased, thenthe rebound stroke is shortened, which causes a frequency at which thepiston strikes against the rebound spring to be increased with theresult that a proper cushioning performance cannot be achieved.

Further, another hydraulic shock absorber having a height adjustingapparatus of a type in which a full length may be changed is known from.for example, Japanese Patent Laid-open 79776/191980. Its schematic viewsare shown in FIGS. 14 and 15. 21 is a damper cylinder, 22 a piston, 23 apiston rod, 24 a suspension spring, 25 a rebound spring, 26 a rubberstop, 27 a spring bearing rigidly fixed along the outer periphery of thepiston rod, 28 a mounting member for either side of the body and axle ofa two-wheeled vehicle, 29 a mounting member for the other side of thebody or axle, 30 a piston for adjusting the height of vehicle serving asone member for adjusting the same, which is fixed to the upper end ofthe piston rod, 31 a cylinder for adjusting the height of vehicle, whichis arranged as the other member for adjusting the same and 32 a springbearing fixed to the outer periphery of the cylinder. When, in a stateprior to increase of the height of vehicle, in which a rider rides, asshown in FIG. 14, a hydraulic oil is supplied to the upper port of thecylinder 31, assuming for ease of understanding that the piston rod 23,hence, the piston 30 stands still and only the cylinder 31 is elevated,the height of vehicle is increased as shown in FIG. 15, so that themounting length is increased from L₁ to L₂. As a result, since theinitially set load of the suspension spring remains the same, when theheight of the vehicle is increased, the rider can experience the samefeeling as when he runs on the flat urban area, but since the totalstroke l_(t) remains the same, a possible major thrust from below, whichcan often be experienced during running on the wasteland, cannot beabsorbed, as in the case of the above-described shock absorber in whichthe initially set load can be changed. Besides, since the mountinglength is made longer by a stroke of the piston 30 as the shock absorberis compressed to maximum extent after the height of vehicle isincreased, a large space becomes necessary between the body of vehicleand the axle.

Also, in the conventional apparatus for adjusting the height of vehiclefor use in a front fork of the two-wheeled vehicle, there are two types:a type in which the initially set load can be changed and a type inwhich the entire length can be changed.

The front fork of a type in which the initially set load may be changedis known from, for example, Japanese Utility Model 160890/1983, which isillustrated in FIGS. 16 to 18. In the same figures, 41 denotes an innerbarrel, 42 an outer barrel, 43 a sheet pipe, 44 a suspension spring, 45a rebound spring, 46 a piston for adjusting the height of vehicle and 47a cylinder for adjusting the height of vehicle. FIG. 16 shows a state inwhich an initially set load is set, i.e., a state in which thesuspension spring 45 is slightly compressed with the height of vehiclenot adjusted as the inner barrel is withdrawn to maximum extent and therebound spring 45 is completely compressed. FIG. 17 shows a state inwhich when a rider rides on a two-wheeled vehicle having a front fork ofFIG. 16 and the suspension spring is compressed the height of vehicle isnot adjusted, which is suitable for running on a flat urban area. FIG.18 shows a state in which as a rider rides on a two-wheeled vehicle andruns on a wasteland a hydraulic oil is supplied to a cylinder foradjusting the height of vehicle 47 formed at a fork bolt 48 of an innerbarrel 41 to displace the inner barrel 41 with respect to an outerbarrel 42 with the result that the height of vehicle is increased fromL₁ to L₂. l_(t) is a total stroke. Actually, its value becomes equal toa value obtained by deducting a basic lengh assumed by, for example, anoil lock collar at the tip end of the inner barrel and the compressedlengthes of the rebound spring and the like. However, in thisembodiment, it is generally represented as l_(t) for convenience ofdiscription. Unless otherwise specified, the same also applies to thefollowing part of specification.

If a displacement vs. load curve of the suspension spring is graphicallyplotted as the initial load of FIG. 16 is set, then K₁ is obtained asseen in FIG. 19. I₁ is the value of the initially set load. If theinitially set load is changed from I₁ to I₂, then the displacement vs.load curve of the suspension spring is shifted to K₂. Now let us assumethat in order to increase the height of the vehicle the piston 46 ofFIG. 17 is downwardly displaced from the upper end position within thecylinder 47 to increase the initial load imposed on the suspensionspring 44, then, since the load imposed thereon is the same as beforeadjusting the height of vehicle, the inner barrel is withdrawn by adisplacement of the piston 46 from the outer barrel with the result thatthe height of the vehicle is increased. In consequence, the rider canfeel rather stiff to ride on the vehicle by such an increased initialload of the suspension spring.

Besides, since the total strokes l_(t) of the hydraulic shock absorberare the same before (FIG. 17) and after (FIG. 18) the height of vehicleis increased, even if he runs into the wasteland and accordinglyincreases the height of vehicle, it cannot absorb large shocks. Inaddition, although the total strokes l_(t) remain the same before andafter the height of vehicle is increased, the position of the stroke ofthe piston in the condition of 1G is altered, so that the distributionsof the stroke become different at the compression and extension sides,and when the height of vehicle is increased as in FIG. 18, then therebound stroke l₂ ' is shortened, which causes a frequency at which thepiston strikes against the rebound spring to be increased with theresult that a proper cushioning performance cannot be achieved.

Further, a front fork provided with an apparatus for adjusting theheight of vehicle of a type in which the entire length can be changed isknown from, for example, Japanese Patent Laid-open 23036/1988. Itsschematic views are shown in FIGS. 20 and 21. In this embodiment, ascrew rod 57 is screwed into a cap 56 at the upper end of an innerbarrel 51, this screw rod being rotatably mounted to a sliding pipe 58which may slidably fit with the outer circumference of the inner barrel51 by means of a handle 59. In a state of FIG. 20, prior to increase ofthe height of vehicle, in which a rider rides and runs into thewasteland, for ease of understanding, let us assume that the innerbarrel 51 stands still, a handle 59 is turned so that the sliding pipe58 may upwardly be moved. At this time, the mounting length of the frontfork is increased from L₁ to L₂ as the suspension spring is compressedto maximum extent. At this time, since the initially set load of thesuspension spring 54 remains the same, the rider can experience the samefeeling as when the height of vehicle is increased as when he runs onthe flat urban area, but since the total stroke l_(t) remains the same,a large thrust from below cannot be absorbed when he runs on thewasteland as in the above-described type in which the initially set loadcan be changed. In addition, since the mounting length of the frontfork, which is compressed to maximum extension after the height of thevehicle is increased, becomes larger by a stroke of the sliding pipe 58than before the height of vehicle is increased, a large space can becomenecessary between the vehicle body and the tire.

Accordingly, it is a principal object of the present invention toprovide a novel shock absorber for use in a vehicle in which drawbacksinherent to the above-described two types are eliminated, i.e., theinitially set load is also not changed as the height of vehicle isincreased and the total stroke is made longer while at the same time therebound stroke remains the same and yet the mounting length of theabsorber assumed as compressed to maximum extent also remains the same.

Another object of the present invention is to provide a novel shockabsorber having an apparatus for manually adjusting the height ofvehicle for use in a vehicle, in which the initially set load of thesuspension spring is not changed as the height of vehicle is increasedwhile at the same time the stroke of piston is made longer and yet themounting length of the shock absorber assumed as compressed to maximumextent is not also changed.

A further object of the present invention is to provide an inexpensiveshock absorber having a hydraulic drive source for driving an apparatusfor adjusting the height of vehicle for use in a vehicle, in which theinitially set load of the suspension spring is not changed as the heightof vehicle is increased while at the same time the stroke of piston ismade longer and yet the mounting length of the shock absorber assumed ascompressed to maximum extent is not also changed, said apparatus using acombination of a pressure tank and a check valve in place of anelectromotive hydraulic pump.

SUMMARY OF THE INVENTION

According to an essential aspect of the present invention, the shockabsorber of the invention for use in a vehicle has an apparatus foradjusting the height of vehicle which permits the mounting length of theshock absorber to be adjusted without changing an initially set load ofa suspension spring, the apparatus being relatively displaced withrespect to one member so that the stroke of the shock absorber may bechanged.

In the apparatus for adjusting the height of vehicle according to thepresent invention, since the mounting length of the shock absorber canbe adjusted without changing the initially set load of the suspensionspring, when the height of the vehicle is increased as a rider runs onthe wasteland, he can enjoy the same comfortable feeling as when he runson a flat urban area. In addition, since the apparatus is so arrangedthat the stroke of the shock absorber may relatively be changed withrespect to one member which serves as a mass positioned above a spring,a major thrust from below can be absorbed when he runs on the wastelandwhile at the same time there is no chance that the piston strikesagainst the rebound spring as is the case with the apparatus of a typein which the initially set load is variable because the amount of arebound stroke of the piston is not also changed, which exerts noadverse effect upon a damping characteristic after it is extended. Inaddition, since the mounting length of the shock absorber is not changedwhen compressed to maximum extent, the vehicle body, clearance and thelike may be similarly designed as in the conventional shock absorber,calling for no extra space which can be caused by the increased heightof the vehicle.

Further, according to one specific embodiment of the shock absorber, theabove-described apparatus has one member for adjusting the height ofvehicle which may serve as a mass at one side of the shock absorber, andthe other member for adjusting the same, which is disposed so as to berelatively displaced with respect to the above-described member whilecomprising one spring bearing displacably disposed with respect to theabove-mentioned other member, the one spring bearing being connected tothe one member which may serve as the mass at one side of the shockabsorber, the other spring bearing fixed to the member which may serveas the other mass of the shock absorber and a suspension spring beingdisposed between both the spring bearings. This arrangement isespecially suitable for a rear cushon of a two-wheeled vehicle and ashock absorber of a four-wheeled vehicle and the like.

In another embodiment of the present invention, the apparatus foradjusting the height of vehicle comprises one member for adjustiung theheight of vehicle which may serve as a mass at one side of the shockabsorber and the other member for adjusting the same, which is disposedso as to be relatively displaced with respect to the above-mentionedmember while comprising one spring bearing fixed to the above-describedother member for adjusting the height of vehicle, the other springbearing disposed so as to be relatively displaced with respect to themember which may serve as the other mass at the other side of the shockabsorber and a suspension spring disposed between the above-describedspring bearings. This arrangement includes a suspension spring theinitially set load of which may be changed within the apparatus of therear cushion for adjusting the height of vehicle. The one springbearing, which is fixed to the other member for adjusting the height ofvehicle, may be displaced therewith while the other spring bearing isdisposed so as to be relatively displaced with respect to the member ofthe shock absorber which may serve as a mass positioned above thespring. Therefore, before and after the height of the vehicle isincreased, the other spring bearing is relatively displaced with respectto the other member of the shock absorber, which may serve as a mass, sothat the initial load of the suspension spring may variously be set.

Further, in another embodiment of the present invention, the shockabsorber has an outer barrel connected to either side of axle andvehicle body, an inner barrel slidably fitted within this outer barrel,the inner barrel being connected to either side of the vehicle body andaxle, and a damper cylinder fixed within the outer barrel, and theabove-described apparatus for adjusting the height of vehicle isarranged by displacably fixing the other end of a piston rod within theinner barrel, which may slide within the damper cylinder by the actionof a piston at the tip end thereof to thereby generate a damping force,a suspension spring being disposed between one spring bearing fixed tothe piston rod and the other spring bearing fixed to the above-mentionedspring bearing. This arrangement is especially suitable for a front forkof the two-wheeled vehicle.

According to the other aspect of the present invention, the shockabsorber having a member mounted at the side of axle or vehicle body,which may be relatively displaced with respect to the piston rod and onespring bearing connected thereto, has a following apparatus for manuallyadjusting the height of the vehicle. Namely, a hollow portion having aninner periphery along which the piston rod may slide is provided withinthe member mounted at the side of the above-described axle or vehiclebody and a threaded portion is formed along the outer periphery thereofwhile an elongated hole pierced through from the outer periphery up tothe hollow portion is formed in the axial direction and a member forconnecting the spring bearing is provided which radially protrudes fromthe piston rod so as to slide within the axial elongated hole of theabove-described member. An adjuster for adjusting the height of vehicleis fitted through the above-mentioned threaded portion formed on theouter periphery of the member mounted to the side of the axle or vehiclebody while a recessed portion engaged with the spring bearing connectingmember is formed at the adjuster protruding from the elongated hole.

According to this apparatus for manually adjusting the height of thevehicle, which is especially suitable for a rear cushion, since theentire height of the vehicle and the stroke can be changed correspondingto the adjusted height of the vehicle without changing the lengthassumed as compressed to maximum extent and the initially set load ofthe suspension spring, when he increases the height of vehicle duringrunning on the wasteland, the same comfortable feeling can be assured tothe rider as when he runs on the flat urban area while a major thrustfrom below, which is often experienced as he runs on the wasteland, canbe absorbed. In addition, since the height of vehicle can be adjusted bymeans of a screw, an reliable adjustment can be assured while it can befixed to any arbitrary adjusted position. Still more, it is light andcompact, and can be manufactured at a low cost.

Besides, the front fork made according to the present invention, whichis arranged so that the member mounted at the side of axle or vehiclebody may relatively be displaced with respect to the piston rod and thespring bearing connected thereto, has a following apparatus for manuallyadjusting the height of vehicle. Namely, a threaded portion and anengaging portion are formed on the outer periphery of the upper portionof the piston rod and a cover member at the end portion of the inner orouter barrel is fitted into the threaded portion while an adjuster foradjusting the height of vehicle, which engages the engaging portion ofthe piston rod to transmit a rotational force while allowing for arelative displacement in the axial direction, is rotatably fitted to theabove-mentioned cover member.

According to another aspect of the invention, the shock absorber for usein a vehicle has a following hydraulic apparatus for adjusting theheight of vehicle. Namely, the apparatus comprises a member mounted atthe side of axle or vehicle body, which may be relatively displaced withrespect to a piston rod of the shock absorber and a spring bearingconnected thereto via a means for transmitting a hydraulic pressure,while comprising a cylinder for adjusting the height of vehicle, whichhas one and the other oil chambers partitioned by the piston foradjusting the height of vehicle, a tank having therein a gas chamber andan oil chamber partitioned by a partitioning member and, a check valvedisposed within a line line which communicates the oil chamber withinthis tank with one oil chamber of the cylinder and a check valvedisposed within a line communicating the oil chamber within the tankwith the other oil chamber, both check valves being disposed indirections inhibiting a reverse flow from the oil chamber within thecylinder, the check valves each having a relief means.

In this arrangement, since there is provided the member mounted at theside of axle or vehicle body which may be relatively displaced withrespect to the piston rod and the spring bearing connected thereto viathe means for transmitting a hydraulic pressure, the height of vehicleand the stroke can correspondingly be changed by the same displacementwithout changing the initially set load of the suspension spring and itsmounting length assumed as compressed to maximum extent. Further, inthis gas-filled hydraulic apparatus for adjusting the height of vehicle,a combination of the check valves and a gas-filled oil tank issubstituted for an electromotive hydraulic pump to obtain an inexpensivehydraulic drive source for the cylinder. Still more, it is highlyoperable and can be fixed at any arbitrary position where the height ofvehicle is adjusted. Furthermore, since the check valves are disposed indirections inhibitting a reverse flow of oil from the oil chamber withinthe cylinder, the fluctuation of pressure caused by a vibration of thevehicle cannot be transmitted to the tank.

In addition, it is preferable that the shock absorber according to thepresent invention has a following hydraulic apparatus for adjusting theheight of vehicle. Namely, a piston for adjusting the height of vehicleis mounted to the piston rod which may displacably be fitted into thecylinder for adjusting the height of vehicle formed at the membermounted at the side of axle or vehicle body, via a means fortransmitting a hydraulic pressure, and a member for engaging this pistonrod to the spring bearing at the side of the piston rod is disposedupwardly of the member mounted at the side of axle or vehicle body.

In this cylinder, since a connecting member for connecting the pistonrod to the spring bearing is disposed upwardly of the member mounted atthe side of axle or vehicle body, it is advantageous from the viewpointof strength as compared with the manually-operated hydraulic rearcushion, in which because the connecting member is disposed upwardly ofthe cylinder an opening becomes necessary for the member at the side ofaxle or vehicle body to be axially displaced, which can in turn weakenthe strength of the mounting member.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal view, in partial cross-section, of a rearcushion for use in an automatic two-wheeled vehicle, which is providedwith an apparatus for adjusting the height of vehicle according to afirst embodiment of the present invention;

FIG. 2 is a schematic view illustrating a state in which prior toincrease of the height of vehicle a rider rides on a two-wheeled vehiclehaving a rear cushion of FIG. 1, so that the suspension spring iscompressed;

FIG. 3 is a schematic view illustrating a condition of the rear cushionof FIG. 2 after the height of vehicle is increased;

FIG. 4 is a longitudinal view in partial cross section, of a rearcushion for use in an automatic two-wheeled vehicle, which is priovidedwith an apparatus for adjusting the height of vehicle according to asecond embodiment of the present invention;

FIG. 5 is a schematic view illustrating a state in which prior toincrease of the height of vehicle a rider rides on a two-wheeled vehiclehaving a rear cushion of FIG. 4, so that the suspension spring iscompressed;

FIG. 6 is a schematic view illustrating a state of a rear cushion ofFIG. 5 after the height of vehicle is increased;

FIG. 7 is a longitudinal view, in cross section, of a front fork of atwo-wheeled vehicle, which is provided with an apparatus for adjustingthe height of vehicle according to a third embodiment of the presentinvention;

FIG. 8 is a schematic view illustrating a state in which a rider rideson a two-wheeled vehicle having a front fork of FIG. 7 without theheight of vehicle being adjusted, so that the suspension spring iscompressed;

FIG. 9 is a schematic view illustrating a state of a front fork of FIG.8 after the height of vehicle is increased;

FIG. 10 is a schematic view illustrating a state of a rear cushion asthe initial load is set, having a coventional apparatus for adjustingthe height of vehicle the initially set load of which may be changed;

FIG. 11 is a schematic view illustrating a state in which a rider rideson a rear cushion of FIG. 10 before the height of vehicle is increased;

FIG. 12 is a schematic view illustrating a state of a rear cushion ofFIG. 11 after the height of vehicle is increased;

FIG. 13 is a graphic view illustrating a displacement vs load curve ofthe suspension spring of a rear cushion having an apparatus foradjusting the height of vehicle of a type in which the initially setload may be changed;

FIG. 14 is a schematic view illustrating a state prior to increase ofthe height of vehicle, in which a rider rides on a rear cushion having aconventional apparatus for adjusting the height of vehicle, in which theentire length can be changed;

FIG. 15 is a schematic view illustrating a state of a rear cushion ofFIG. 14 after the height of vehicle is increased;

FIG. 16 is a schematic view illustrating a state of a conventional frontfork of a type in which the initially set load may be changed as theinitially set load is set;

FIG. 17 is a schematic view illustrating a state before the height ofvehicle is not adjusted, in which a rider rides on a two-wheeld vehiclehaving a front fork of FIG. 16, so that the suspension spring iscompressed;

FIG. 18 is a schematic view illustating a state of the front fork ofFIG. 17 after the height of vehicle is increased;

FIG. 19 is a graphic view of a displacement vs. load curve of thesuspension spring of a front fork having an apparatus for adjusting theheight of vehicle of a type in which ther initially set load may bechanged;

FIG. 20 is a schematic view illustrating a state prior to increase ofthe height of vehicle, in which a rider rides on a two-wheeled vehiclehaving a conventional front fork the entire length of which may bechanged;

FIG. 21 is a schematic view illustrating a state of the front fork ofFIG. 20 after the height of vehicle is increased;

FIG. 22 is a longitudinal view in partial cross section illustrating astate of a rear cushion prior to increase of the height of vehicle,having an apparatus for adjusting the height of vehicle according to thepresent invention;

FIG. 23 is a longitudinal view in cross section illustrating a state ofthe rear cushion of FIG. 22 after the height of vehicle is adjusted;

FIG. 24 is a lateral view in cross section taken along line XXIV--XXIVof FIG. 23;

FIG. 25 is a longitudinal view of a front fork prior to adjustment ofthe height of vehicle, having an apparatus for adjusting the height ofvehicle according to the present invention;

FIG. 26 is a longitudinal view in cross section illustrating a state ofthe front fork of FIG. 25 after the height of vehicle is adjusted;

FIG. 27 is a lateral view in cross section taken along line XXVII--XXVIIof FIG. 25;

FIG. 28 is a lateral view in cross section taken along lineXXVIII--XXVIII of FIG. 25;

FIG. 29 is a partial cross-sectional view of a rear cushion of atwo-wheeled vehicle prior to adjustment of the height of vehicle havingan apparatus for adjusting the height of vehicle according to theinvention;

FIG. 30 is a partial cross-sectional view illustrating a state of therear cushion of FIG. 29 after the height of vehicle is increased;

FIG. 31 is a partial cross-sectional view of a front fork of atwo-wheeled vehicle prior to adjustment of the height of vehicle, havingan apparatus for ajusting the height of vehicle according to the presentinvention;

FIG. 32 is a partial cross-sectional view illustrating a state of thefront fork of FIG. 31 after the height of vehicle is increased; and

FIG. 33 is a hydraulic circuit diagram for operating gas-filledapparatus 30 and 60 for adjusting the height of vehicle of a front forkand a rear cushion.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention is now hereinafter described in greater detailwith specific reference to preferred embodiments in conjunction with theaccompanying drawings.

FIG. 1 shows a rear cushion, in partial cross section, for use in anautomatic two-wheeled vehicle having an apparatus for adjusting theheight of vehicle according to a first embodiment of the presentinvention.

A piston 142 is slidably fitted at the tip end portion of a piston rod143 which passes through the bottom portion of a damper cylinder 141 sothat it may slide within the cylinder 141. A means for generating adamping force at the extending side and a means for generating a dampingforce at the compression side are respectively attached, as usual, tothe upper and lower surfaces of the piston 142. Reference numeral 145 isa rebound spring and 146 a damper rubber. A suspension spring 144 isfitted between a spring bearing 147 screwed into the damper cylinder 141and a cylindrical spring bearing 150 slidably fitted around an apparatus160 for adjusting the height of vehicle, which will be described later.In this case, the masses existing above the spring are the springbearing 147 and the damper cylinder 141 while those existing below thespring are the piston 142, piston rod 143, apparatus 160, spring stopper164 and the spring bearing 150.

The apparatus for adjusting the height of vehicle according to thepresent invention has a spring bearing 150 slidably fitted about theouter periphery of a cylinder 161 for adjusting the height of vehicle,which is arranged as the other member for adjusting the height ofvehicle and a mounting member 149 at the side of the axle 149 isintegrally formed at the lower end of the cylinder 161 for adjusting theheight of vehicle. The piston rod 143 passes through a cap 162 fixed atthe upper end of the cylinder 161 and the lower end of the cylinder 161and a piston 163 for adjusting the height of vehicle attached to thepiston rod 143 is slidably fitted within the cylinder 161. The springstop 164 is fixed to the tip end of the piston rod downwardly protrudingfrom the cylinder 161 to engage the spring bearing 150. Ports 165 and166 provided through the periperal surface of the cylinder 161 eachcommunicating with the upper and lower chambers of the piston 163 viapassageways 167 and 168.

The operation of the apparatus of a rear cushion thus arranged is nowdescribed with reference to FIGS. 2 and 3. FIG. 2 shows a state of therear cushion as the suspension spring 144 is compressed under the actionof the weight of a rider who rides on an automatic two-wheeled vehicle,which state assures that his feet can easily reach the ground to stopthe vehicle and is suitable for running on a flat urban area. This stateis one prior to adjustment of the height of vehicle, in which apressurized oil is supplied from the port 165 into the upper chamber ofthe cylinder 161. At this time, the total stroke l_(t) covers from thelower surface of the piston 142 of the damper cylinder 141 up to theupper surface of the stopper rubber 146 as yielded to its maximumextent.

When the rider runs into the wasteland, the pressurized oil is suppliedfrom the port 166 below the cylinder 161 into the cylinder 161 whilebeing discharged form the upper port 165. In this case, assuming forease of understanding that the piston rod 143 stands still, only thecylinder 161 is downwardly slided within the spring bearing 150 untilthe mounting length is increased from L₁, into L₂ to increas e theheight of vehicle. At this time, since the spring bearing 150 alsostands still, the suspension spring 144 remains not to be displaced andits initially set load does not change. In addition, since the pistonrod also retain a still condition and only the cylinder is downwardlydisplaced with respect to the piston rod, the stroke l_(t) of the shockabsorber is increased. Further, since the position of the piston in 1Gcondition within the damper cylinder 141 remains the same, a magnitudeof the rebound stroke within the damper cylinder also remains the same.The mounting length of the rear cushion is increased by the amount ofstroke of the cylinder, as can readily been understood from FIGS. 2 and3.

Next, a second embodiment of the present invention is described ingreater detail with reference to the accompanying drawings, in whichFIG. 4 illustrates a rear cushion in partial cross section having anapparatus for adjusting the height of vehicle according to the presentinvention for use in an automatic two-wheeled. A piston 242 is fitted atthe tip end of a piston rod 243 passing through the bottom portion of adamper cylinder 241 so as to be slided within the cylinder 241. A meansfor generating a damping force at the extention side and a means forgenerating a damping force at the compression side are respectivelymounted, as usual, at the upper and lower surfaces of the piston 242.Reference numeral 245 is a rebound spring, 246 a damper rubber, 247 amounting member at the side of the body of the vehicle and 248 amounting member at the side of axle.

According to the present invention, a portion 250 for adjusting theheight of vehicle is provided at the lower portion of this rear cushionwhile a portion 260 for adjusting the initial load of the suspensionspring is provided at the upper portion thereof, the suspension spring249 being suspended therebetween.

The portion 250 for adjusting the height of vehicle according to thepresent invention has a cylinder 252 for adjusting the height of vehiclewhich may serve as the other member for adjusting the height of vehicle,with which the mounting member 251 at the side of axle is integrallyformed, so that a piston 253 for adjusting the height of vehicle, whichmay serve as one member for adjusting the height of vehicle, may beslided within the cylinder 252, the piston 253 being fixed to the tipend of the piston rod 243 downwardly extending within the cylinderthrough a cap 254 of the cylinder. At the outer periphery of thiscylinder 252 is fixed one spring bearing 255 by means of a stop springto support the lower end of the suspension spring. At the outerperiphery of the cylinder 252 are attached a port 256 which maycommunicate with the upper chamber of the piston 253 and a port 257which may communicate with the lower chamber of the piston 253.

In addition, the apparatus for adjusting the height of vehicle accordingto the present invention has a portion 260 for adjusting the initialload, which comprises a spring-adjusted annular cylinder 261 fixed tothe outer periphery of the damper cylinder 241, and a spring-adjustedannular piston 262 which may be slided within that cylinder 261. A port264 for supplying the pressurized oil is provided through the uppersurface of the spring-adjusted cylinder 261. The spring-adjusted piston262 has a guide portion 263 which may slide on the outer periphery ofthe damper cylinder 241. The spring-adjusted piston also serves as aspring bearing to support the suspension spring 249 at the lower endthereof.

Besides, a rear cushion having the apparatus for adjusting the height ofvehicle according to the present invention has an advantage over one ofthe, for example, first embodiment, in which the upper end of the pistonrod passing through the cylinder is connected to the spring bearingslidably fitted about the cylinder in that it can be shortened in entirelength and be compact because the piston rod does not protrude from thecylinder therethrough.

The operation of the apparatus 250 and 260 of a rear cushion thusarranged is described with reference to FIGS. 5 and 6.

FIG. 5 is a state of a rear cushion according to the present inventionas a rider rides on an automatic two-wheeled vehicle and the suspensionspring 249 is compressed, which is a state prior to adjustment of theheight of vehicle, in which a pressurized oil is supplied from the port256 into the upper chamber of the cylinder 252 for adjusting the heightof vehicle, the state being suitable for running on the flat urban areabecause his feet can readily reach the ground.

At this time, the total stroke 1_(t) covers from the lower surface ofthe piston 242 of the damper cylinder 241 up to the upper surface of thestopper rubber 246 as compressed. When he runs into a wasteland in thisstate, a pressurized oil is supplied from the port below the cylinder252 into the cylinder 252 while being discharged from the upper port 256(FIG. 6). At this time, for ease of understanding, assuming that thepiston rod 243 stands still, then only the cylinder 252 is downwardlymoved with the result that the mounting length is changed from L₁ to L₂to increase the height of vehicle. At this time, since the springbearing 255 is fixed to the cylinder 252, the suspension spring 249 ismade longer and its initially set load is changed. In order to correctthis change, a pressurized oil of an amount corresponding to thedisplacement of the spring bearing at the side of axle is supplied fromthe port 264 of the portion 260 for adjusting the suspension spring tolower the piston 262 for adjusting the spring. Therefore, the initiallyset load of the suspension does not chage. Since the position of thepiston in the 1G state within the damper cylinder 241 is not changed,the rebound stroke 1₂ within the damper cylinder is not also changed.Also, the mounting length of the rear cushion as compressed to maximumextent remains the same, as readily understood from FIGS. 5 and 6.

Incidentally, in the state of FIG. 5 (running on the urban area) and thestate of FIG. 6 (running on the wasteland), a proper amount of oil issupplied to the port 264 at the portion 260 for adjusting the suspensionspring, so that the initial load of the suspension spring may variouslybe set.

Next, a third embodiment of the present invention is described in detailwith reference to the drawings.

FIG. 7 illustrates a longitudinal view, in cross section, of a frontfork for use in an automatic two-wheeled vehicle, having an apparatusfor adjusting the height of vehicle according to the present invention.

Within the outer barrel 322 mounted at the side of axle is slidablyfitted an inner barrel 321 mounted at the side of the body of vehicle.At the bottom portion of the outer barrel 322 is rigidly fixed a dampercylinder 323 via an oil lock piece 324 by means of a bolt 326 screwedinto an end piece 325. As usual, a bottom piece 327 provided with adamper means at the compression side is attached at the upper portion ofthe end piece 325. A piston rod 329 upwardly extends within the innerbarrel 321 from a piston 328 which may be slided within the dampercylinder 323 through a rod guide 330 at the top portion of the dampercylinder 323. A suspension spring 333 is suspended between a springbearing 331 fixed to the pistoin rod 329 and a suspension bearing 332fixed to the upper end of the damper cylinder 323. As usual, a dampermeans at the extension side is provided at the piston 328. 334 denotes arebound spring. The above-described front fork is a known type called adamper-built-in front fork or cartridge type front fork. Massespositioned above the spring are the inner barrel 321, apparatus 340 foradjusting the height of vehicle, piston rod 329 and piston 328 whilemasses positioned below the spring are the outer barrel 322, oil lockpiece 324 and the damper cylinder 323.

The apparatus for adjusting the height of vehicle according to thisembodiment is provided at the upper end portion of the inner barrel 321.The apparatus 340 for adjusting the height of vehicle has a cylinder 341for adjusting the height of vehicle, which is formed in the interior ofa fork bolt 342 inserted and fixed at the upper end of the inner barrel321. At the upper end of the piston rod 329 extending through a cover343 at the lower end of the cylinder 341 into the cylinder 341 is fixeda piston 344 for adjusting the height of vehicle, which is slidablyfitted with the cylinder 341. On the outer periphery of the fork bolt342 is formed an annular groove 345, which, on the one hand,communicates with the lower chamber of the cylinder 341 through athrough-hole 346 and, on the other hand, communicates with a port 348 ofa ring member 347 through a through hole and an annular groove 350.Meanwhile, a port 351 is bored through the upper chamber of the cylinder341.

Next, the operation of the apparatus for adjusting the height of vehiclearranged as above is described with reference to FIGS. 8 and 9. FIG. 8illustrates a state of a front fork prior to adjustment of the height ofvehicle, in which a rider rides on an automatic two-wheeled vehicle.When he runs from the flat urban area into the wasteland, a pressurizedoil is supplied from the port 351 to the upper chamber of the cylinder341. At this time, for ease of understanding, assuming that the piston344 and the piston rod 329 integral therewith stand still, the innerbarrel 321 is upwardly moved within the outer barrel 322 with the resultthat a mounting dimension between a bracket mounted at the vehicle body(not shown) fixed on the outer periphery of the inner barrel and an axle(not shown) fixed to the lower portion of the outer barrel is madelonger to increase the height of vehicle. At this time, although thetotal stroke is increased from 1₁ to 1₂ by a stroke of the piston 344,since the suspension spring is not compressed, its initially set loaddoes not change. Since the position of the piston in the 1G conditionwithin the damper cylinder 323 remains the same, the amount of a reboundstroke within the damper cylinder also remains the same. At the time ofmaximum compression as the oil lock collar at the tip end of the innerperiphery of the inner barrel 321 fits with the oil lock piece 324 atthe lower end of the outer barrel, the dimensions of the front fork arethe same as the height of vehicle is lowered as in FIG. 8, and asincreased as in FIG. 9.

FIGS. 22 and 23 respectively illustrate a rear cushion of an automatictwo-wheeld vehicle according to a fourth embodiment of the presentinvention, having an apparatus 420 for manually adjusting the height ofvehicle using a screw. The cross section of FIG. 23 forms an angle of90° with respect to the one of FIG. 22.

This rear cushion 410 has a damper cylinder 411 and a piston rod 412downwardly protruding from a slidable piston (not shown) through thisdamper cylinder. One bearing 413 is connected to the piston 412 via theapparatus 420 for adjusting the height of vehicle, which will bedescribed later, and the other spring bearing 414 is fixed to thecylinder 411, a suspension spring 415 being disposed therebetween.Incidentally, 416 denotes a mounting member at the side of the vehiclebody and 417 a mounting member at the side of axle.

The apparatus 420 for adjusting the height of vehicle according to thepresent invention is provided at the lower portion of the rear cushionand a hollow portion 421 having an inner periphery through which thepiston rod slides is provided at the mounting member 417 at the side ofaxle. A threaded portion 422 is formed on the outer periphery andelongated holes 423, 423' pierced through from the outside in the axialdirection up to the hollow portion 421 are provided at positions opposedto each other. At the lower end of the piston rod 412 is attached a key424 serving as a member for connecting the spring bearing so as toradially protrude in both directions, the key being vertically slidablewithin the axial elongated holes 423, 423' of the mounting member 417 atthe side of axle. At the threaded portion 422 of the outer periphery ofthe mounting member is screwed an adjuster 425 for adjusting the heightof vehicle, on which the inner periphery of which is formed a recessedportion 416 which both ends of the key 424 protruding from the pistonrod 412 enter.

An intermediate member 427 is interleaved between the adjuster 424 andthe spring bearing 413. 428 denotes a bearing of the damper rubber,which is screwed into the threaded portion 422 at the upper end of themounting member 417 and 429 a damper rubber.

The operation of the apparatus 420, arranged as above, for manuallyadjusting the height of vehicle using a screw is hereinafer described.FIG. 22 shows a state prior to adjustment of the height of vehicle,which is suitable for running on the flat urban area. When the riderruns on the wasteland, the adjuster 425 is turned in one direction. Inthis case, for ease of understanding, assuming that the piston rod 412stands still, since the key 424 of the piston rod engages the elongatedaxial holes 423, 423 of the mounting member 417 to inhibit itsrotastion, by rotation of the adjuster 425, only the mounting member 417engaging therewith is downwardly shifted with respect to the piston rod412 so that the mounting length is increased by the adjusted height ofvehicle from L₁ up to at most L₂ (FIG. 23). At the same time, the strokeis also increased by the adjusted height from S₁ up to at most S₂.Consequently, the height of vehicle can be set to arbitrary position.Since the spring bearing 413 remains still, the suspension spring 415remains still without being displaced and therefore its initially setload does not change.

Next, the front forks 30 of an automatic two-wheeled vehicle arerespectively shown in FIGS. 25 and 26 having an apparatus according to afifth embodiment for manually adjusting the height of vehicle using ascrew. The cross section of FIG. 26 forms an angle of 90° with respectto the one of FIG. 25.

An inner barrel 432 having a mounting member at the side of vehicle bodyat the upper portion thereof is slidably fitted within an outer barrel431 having a mounting member at the side of axle (not shown) at thelower end thereof while a piston 434 is slidably fitted with a dampercylinder 433 upwardly extending from the bottom portion of the outerbarrel 431, and a piston rod 435 upwardly extends from this piston 434through a rod guide 433a of the damper cylinder 433 to be connected to acover member 436 at the upper end of the inner barrel 432. A springbearing 437 is mounted at the upper end of the damper cylinder 433 and asuspension spring 439 is disposed between this spring bearing 437 andthe other spring bearing 438 fixed to the piston rod 412. 440 denotes arebound spring.

The apparatus 441 according to the present invention is provided at theupper portion of the inner barrel 432 and a threaded portion 442 isprovided on the outer periphery at the upper portion of the piston rod435. As seen in FIG. 27, parallel surfaces 443, 443' oppoed to eachother at the same distance from the center of axis are formed as theengaging portions. The threaded portion 442 of the piston rod 435 isfitted with a femal thread portion 444 at the lower end portion of acover member 436 fixed to the upper end of the inner barrel 432. Inaddition, a columnar adjuster 446 is fitted with a cylindrical hole 445formed in the cover member 436, this adjuster being connected to thepiston rod 435 by means of a groove (see FIG. 27) having inner surfaces447, 447' which contact both surfaces 43, 443' of the threaded portion442. Incidentally, a stopper pin 448 for limiting an increase of theheight of vehicle is attached at the upper end of the piston rod 435 sothat the rod 435 may not be removed. 449 is an end plate and 450 a cap.

Now, the operation of the apparatus 41 arranged as above is described.

FIG. 25 shows a state prior to adjustment of the height of vehicle,which is suitable for running on the urban area. When a rider runs fromthis condition into the wasteland, if an adjusting knob 446a of theadjuster 446 is turned, since both flat surfaces 443, 443' of thethreaded portion 442 of the piston rod 435 are fitted with the groove ofthe adjuster, the piston rod 435 is rotated together with the adjuster446. Considering that the piston rod 435 is rotated at its positionwithout being moved vertically, the femal thread portion 444 fitted withthe threaded portion 442, hence the cover member 436 is upwardly movedtogether with the adjuster 446 so that the height of vehicle isincreased from L₁ by the adjusted height. At the same time, the strokeof the inner barrel 433 is also increased from S₁ to S₂ by the adjustedamount of height. FIG. 26 shows a state in which the stopper pin 448 ofthe piston rod 435 abutted against the bottom of the cylindrical hole445 of the adjuster 436, the height of vehicle being adjusted to maximumextent. In the apparatus of the present invention, since the suspensionspring 439 is not compressed, its initially set load cannot change.Besides, as the time of maximum compression as the oil lock collar atthe lower end of the inner barrel 432 fits with the oil lock piece atthe lower end of the outer barrel 431, the dimensions of the front forkare the same before (FIG. 25) and after (FIG. 26) the height of vehicleis adjusted.

FIGS. 29 and 30 respectively show the lower portion of a rear cushion520 of an automatic two-wheeled vehicle according to a sixth embodimentof the invention, having a hydraulic appraratus for adjusting the heightof vehicle. The cross section of FIG. 30 forms an angle of 90° withrespect to the one of FIG. 29.

This rear cushion has a piston rod 523 protruding from a piston 522which may slide within a damper cylinder 521 (see FIG. 33). A suspensionspring 526 is disposed between an upper spring bearing 524 fixed to thedamper cylinder 521 and a lower spring bearing 525 attached to thepiston rod 523. 527 denotes a mounting member at the side of vehiclebody, 528 a mounting member at the side of axle and 529 a damper rubber.

A gas-filled hydraulic apparatus 530 for adjusting the height of vehicleaccording to the present invention has a piston for adjusting the heightof vehicle, which is fixed to the piston rod 523 via a rod 531, and acylinder 533 for adjusting the height of vehicle, which is formed at themount 528 at the side of axle. An opening at the upper end of thecylinder 533 is closed by means of a cover 534. The spring bearing 525is connected to the piston rod 523 via a planar connecting member 535upwardly protruding from the cylinder 533 of the member 528, on which issupported a stopper rubber 529 via a stopper rubber sheet 536 having aplurality of leg portions 536a. An opening portion 535a through whichthe leg portions 536a pass is provided at the connecting member 535 sothat the stopper rubber sheet 536 may be displaced together with thecylinder 533. 537 denotes a lock nut.

A tube joint 539 is connected to a port B' leading to a lower chamber ofthe cylinder 53, which is defined by the piston 532 while a tube joint542 of a port A' is connected at a notched portion 540 communicatingwith an upper chamber via a through hole 541 extending through the wallof cylinder.

Next, FIGS. 31 and 32 respectively show a front fork 550 of an automatictwo-wheeled vehicle according to a seventh embodiment of the presentinvention, having an apparatus for adjusting the height of vehicle.

An inner barrel 552 is slidably fitted through an outer barrel 551 (seeFIG. 33) and a piston 554 is slidably fitted within a damper cylinderextending from the bottom portion of the outer barrel extending from thebottom portion of the outer barrel 551, a piston rod 555 upwardlyextending through a rod guide 553a from this piston. A suspension spring556 is disposed between a spring bearing 557 at the upper end of thedamper cylinder and a spring bearing 558 fixed to the piston rod 555.

In this apparatus of the front fork according to the invention, a hollowportion the lower side of which is open is formed at the lower portionof a cover member 561 screwed into the upper end of the inner barrel552, which is a member mounted to the side of vehicle body, a cylinder562 for adjusting the height of vehicle being inserted from below intothis hollow portion. A piston 563 for adjusting the height of vehicle isslidably fitted wtin this cylinder 562. A rod 564 connected to thepiston rod 555 by means of a screw is screwed into this piston 563.Further, at the lower side of the cover member 561 is screwed an outerbarrel 565 having an inner periphery spaced apart from the outerperiphery of the cylinder 562 to thereby form an annular passageway 566through which oil flows, between the outer barrel 565 and the cylinder562. An end plate 567 is attached to the lower end of the cylinder 562and a cap 568 for supporting the end plate 567 is screwed into the outerbarrel 565.

As an oil passageway for supplying a pressurized oil to this cylinder562 is connected a port B to an oil passageway 569 leading to an upperoil chamber defined by the piston 563 while a through hole 571 leads toa lower chamber, this through hole communicating via the above-mentionedannular oil passageway 566 with an upper oil passageway 572, from whichthe through hole further communicates via an oil passageway 573 with aport A.

FIG. 33 shows a hydraulic circuit for operating apparatus 530 and 560 ofthe front fork and rear cushion for adjusting the height of vehicle. 581is a tank having therein a gas chamber 583 and an oil chamber 584partitioned by a resilient partitioning member 582, a pressurized gas ofabout 50 to 60 kg f/cm² being sealed therein. At a controller portion585 are provided an oil chamber 584 within the tank, check valve 586disposed along lines a,a' connecting the port A of the lower side oilchamber of the front fork and the port A' of the upper side oil chamberof the rear cushion, oil chamber 584 within the tank, check valve 587disposed along lines b,b' connecting the front fork, port B of the upperside oil chamber of the rear cushion and the port B' of the lower sideoil chamber of the same and buttons 588 and 589 for respectivelyincreasing and lowering the height of vehicle, which are the check valverelieving means for opening these check valves 586, 587. These checkvalves 586, 589 are both disposed in directions inhibitting a reverseflow from the oil chamber of the cylinder.

The operation of the above-described apparatus of the rear cushion isdescribed mainly with reference to FIG. 33.

FIG. 29 (rear cushion) and FIG. 31 (front fork), which referrs to thestates prior to increase of the height of vehicle, respectivelyillustrate a state in which a pressure of the sealed gas within the tank581 passes through the check valves 586, 587 and the lines a, b and a,'b' to act on the upper and lower surfaces of the pistons 532, 563 whilea rider is riding on the vehicle, so that a balance of weight isachieved. In this state, the fluctuation of the pressure caused by avibration of the upper and lower surfaces of the pistons 532 and 563 isinhibitted from being transmitted to the oil chamber 584 of the tank 581because of the presence of the check valves 586 and 587. At this time,since the upper and lower chambers of the piston 532 of the rear cushioncommunicate with each other through the line a' which may communicateswith the line a, and the line b' which may communicate with the line b,the lower chamber of the piston 563 of the front fork and the upperchamber of the piston 532 of the rear cushion communicate with eachother with the result that the same pressure is achieved therein. Hence,an area where the pressure is apllied to the piston of the rear cushionsubjected to the pressure is correspondingly increased because it issubjected to a great suspending load.

When the rider runs from the urban area into the wasteland, if he getsoff the vehicle and connects a front portion of the vehicle body to thesuspending inner barrel 552 of the front fork, for eample, raises ahandle or the like with respect to the outer barrel 551, wheel and thelike, the oil chamber below the piston 563 is compressed with the resultthat the oil passes from the port A through the line a to act on thecheck valve 586. At this time, since the check valve 586 inhibits thisflow of oil, if he presses the button 588 to let a ball of the checkvalve off a valve seat to open it, a hydraulic oil passing therethroughpushes up the check valve 587 to pass through the line b to flow into anoil chamber above the cylinder 563 of the front fork so that thecylinder 562 and the inner barrel connected therewith may be raised withrespect to the outer barrel 551. Also, in the rear cushion, if he liftsthe rear body of vehicle and rocks the body in the forward and rearwarddirections to compress the upper oil chamber of the piston 532, thehydraulic oil passes through the oil passageway a' to reach the checkvalve 586. At this time, since the check valve 586 is separated off theseat portion lifted by a push rod at the tip end of the button 588 forlifting the height of vehicle, the oil passes through the check valve586 to reach the check valve 587. Since the check valve 587 opensagainst this flow of oil, the oil passes through the check valve 587 andthe passageway b' to flow into the lower chamber of the piston so thatthe cylinder 53 is downwardly displaced with respect to the piston 532to increase the height of vehicle. Thus each mounting length of thefront fork and the rear cushion is increased so that the height ofvehicle is increased from L₁ to L₂, as shown in FIGS. 32 and 30. In thisstate, the fluctuation of pressure within the upper and lower chambersof the pistons 532 and 563 is prevented by means of the chech valves 586and 587 and is not transmitted to the tank. That is, the height ofvehicle is locked in that increased condition.

Next, when the height of vehicle is lowered from this condition, if abutton 589 for lowering the height of vehicle is pressed to relieve thecheck valve 587, then the lines b and b' communicate with the lines aand a' via the check valve 586. At this time, if the rider applies orrelieves his weight back and forth, keeping his riding posture, to movethe inner barrel 552 and the cylinder 562 up and down, then thehydraulic oil within the upper chamber of the piston 563 passes from theline b through the check valves 587 and 586 into the line a to flow intothe lower oil chamber of the piston 563 so that the cylinder 562 and theinner barrel 552 are lifted. Similarly, the hydraulic oil within thelower chamber of the piston is compressed and passes through the line b'and the check valves 587 and 586 and further the line a' to flow intothe upper oil chamber of the piston so that the cylinder 533 mayupwardly move with respect to the piston 532. As a result, the height islowered from L₂ to L₁. Since the enlarged and contracted chambers (theopposite is the case as the height of vehicle is decreased) of the frontfork and rear cushion are connected, as the height of vehicle is raised,by the lines a and a' and the lines b and b', an excellent balancebetween the heights of the vehicle taken in lateral direction caneffectively be achieved by properly setting the area of the piston towhich the pressure is applied.

As in this embodiment, when the oil chamber of the piston of the frontfork and that of the cylinder of the rear cushion are branched at thedownstream of the check valves 586 and 587, since the pressurizing tank581 and the check valves 586 and 587 can be used in common, only onepressurizing tank 581 is necessary thus reducing the installation cost.

It is apparent that the pressure tank and the check valve can berespectively provided by one to the front fork and the rear cushion.

What is claimed is:
 1. A shock absorber for a vehicle comprising:anouter barrel connected to one of a vehicle body and an axle; an innerbarrel connected to the other of said axle and vehicle body, said innerbarrel being slidably fitted within said outer barrel; a damper cylinderdisposed within one of said inner and outer barrels; a piston rod; afirst end of said piston rod displaceably fixed to the other of saidouter and inner barrels; a second end of said piston rod; a pistonconnected to the second end of said piston rod and disposed to slidewithin said damper cylinder; a first spring bearing secured to saidpiston rod; a second spring bearing secured to said damper cylinder;and, a suspension coil spring interposed between said first and secondspring bearings.
 2. A shock absorber for a vehicle as set forth in claim1 further comprising:cylinder means fixed to said outer barrel or innerbarrel and filled with oil; piston means fixed to the first end of saidpiston rod whereby to define two chambers; and ports connected to eachof chambers whereby said piston rod is displaceable with respect to atleast one of said outer and inner barrels by supplying pressurized oilinto each of said chambers alternately through said ports.